JPS6040880Y2 - Internal combustion engine cooling fan - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cooling fan in which serrations are formed on at least the leading edge side of a plurality of fan blades around a shaft that is driven and rotated.

Among the noises generated by internal combustion engines, the noise generated by cooling fans is difficult to reduce by using enclosures or the like.

This is because the cooling air must be discharged to the outside, which causes noise to be emitted to the outside.

Although it is not clear what causes the noise produced by cooling fans, it is caused by the movement of one fan blade creating turbulence or vortices that cause subsequent fan blades to collide with the turbulence or vortices. It is estimated that

To this end, according to the prior art, sawtooth-shaped serrations 4 are applied to the leading edge 3 on the rotational direction α side of the fan blade 1 attached to the boss 2, as shown in FIG. Devices that reduce fan noise caused by vortices are known.

Although the conventional technology shown in FIG. 1 can produce some effects, it is not always possible to sufficiently reduce noise because air turbulence and vortices are generated on both sides of the fan blade 1. I couldn't.

For example, in Japanese Utility Model Application Publication No. 52-115905, an auxiliary blade is provided on either or both of the suction side and the discharge side, and the front edge of the auxiliary blade is placed closer to the rotation center of the fan than the rear edge. Some suggestions have been made.

However, this technology aims to increase the effective air blowing effect and the amount of air blown, and forces the flow to avoid rear obstacles by radially outward flow, and with regard to noise, the vortex turbulent flow occurs, and the reduction effect cannot be achieved because the vortices and turbulent flow cannot be prevented.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a cooling fan for an internal combustion engine that can prevent the generation of vortices and turbulence due to fan blades, thereby reducing noise.

According to the present invention, in a cooling fan in which serrations are formed at least on the leading edge side of a plurality of fan blades around a shaft that is driven and rotated,
A plurality of concave and convex stripes are formed concentrically on both sides of the fan blade along the rotation direction.

Therefore, the airflow generated by the rotation of the fan is rectified by the multiple uneven concentric lines on both sides of the fan blade, and the turbulence and vortices generated by the front fan blade are removed from the leading edge side of the fan blade. The energy of collisions L with the serrations, turbulence, and vortices is reduced, and the flow is rectified by the concave and convex strips of the next fan blade, resulting in a significant reduction in noise.

Embodiments of the present invention will be described below with reference to FIGS. 2 to 7.

FIG. 2 shows one fan blade 1 constituting a cooling fan, with sawtooth-shaped serrations 4a on the reaching edge 3 side and the training edge 6 side.
4b is formed.

Further, according to the present invention, as shown in FIG.
A plurality of concentric circles consisting of convex portions 5a and concave portions 5b alternately formed in the radial direction along the rotational direction on both sides of the fan blade 1 from the serrations 4a on the reaching edge 3 side to the serrations 4b on the training edge 6 side. A concavo-convex line 5 having a shape is formed.

Therefore, both side surfaces of the fan blade 1 are not planar but wavy due to the uneven stripes 5.

The fan blade 1 has a boat-shaped cross section along the circumferential direction, as shown in FIG. 4, and this cross-sectional shape is the same as that of the prior art.

Note that when forming the uneven strips 5, they can also be formed into gentle uneven stripes as shown in FIG.

Next, the operation of the present invention will be explained with reference to FIG.

When the fan blade 1 is rotated, the turbulent flow or vortex V caused by the front fan blade 1 collides with the serrations 4a of the leading edge 3 of the plurality of adjacent fan blades 1' and is easily rectified. 5.

As described above, according to the present invention, the vibration of the fan blade 1 itself is reduced due to the rectifying effect of turbulent flow and eddies, and the vortex V can be effectively destroyed by the rectifying effect of the air flow, resulting in a large Noise reduction can be measured.

Furthermore, energy loss due to noise generation can be reduced.

There are also side effects such as smoother rotation of the fan and increased durability of the conduction belt.

FIG. 7 is a graph showing the effects of the present invention.

In the figure, the shape of the fan blade of the cooling fan is changed, and the horizontal axis shows the flow rate Q, and the vertical axis shows the measured value of the noise level.

In the figure, when the blade is not provided with a serrations,
A comparison was made between a case in which B serrations were formed on a fan blade, and a case in which a concavo-convex strip according to the present invention was formed in a fan blade in addition to C serrations.

The results show that in case C of the present invention, the noise generation is several decibels lower at the same flow rate.

[Brief explanation of drawings]

Fig. 1 is a partial front view of a cooling fan according to the prior art, Fig. 2 is a partial front view showing an embodiment of the cooling fan according to the present invention, Fig. 3 is a side view thereof, and Fig. 4 is a partial front view of a cooling fan according to the present invention. 5 is an explanatory diagram showing the action of the cooling fan according to the present invention, FIG. 6 is a partial sectional view showing another embodiment of the present invention, and FIG. 7 is a cross-sectional view taken along line A-A in the figure. It is a graph showing the effect of such a cooling fan. 1...Fan blade, 2...Boss,
3... Leading edge, 4... Serration, 5... Concave and convex stripes, 6... Training edge.

Claims (1)

[Scope of utility model registration request] In a cooling fan in which serrations are formed on at least the leading edge side of a plurality of fan blades around a shaft that is driven and rotated, a plurality of concave and convex stripes are provided on both sides of the fan blade in concentric circles along the direction of rotation. A cooling fan for internal combustion engines that is characterized by its fierce performance.